After Fedora, Ubuntu has now also announced how it's going to handle the nonsense called "Secure" Boot. The gist: they'll use the same key as Fedora, but they claim they can't use GRUB2. "In the event that a manufacturer makes a mistake and delivers a locked-down system with a GRUB 2 image signed by the Ubuntu key, we have not been able to find legal guidance that we wouldn't then be required by the terms of the GPLv3 to disclose our private key in order that users can install a modified boot loader. At that point our certificates would of course be revoked and everyone would end up worse off." So, they're going to use the more liberally licensed efilinux loader from Intel. Only the bootloader will be signed; the kernel will not.

So before asking Microsoft about making it easy for other oses to boot or install, please ask Apple.

You're missing the point. MS requires these modifications as part of their compatibility program and it it likely to affect the general-purpose PC market. This means users may unexpectedly not be able to install the software they like.

In contrast, everyone who buys an Apple iPad already knows that he got fucked. It is also common knowledge that special-purpose systems like smartphones cannot be freely modified, they mostly already ship their own proprietary versions of secure boot.

You're missing the point. MS requires these modifications as part of their compatibility program and it it likely to affect the general-purpose PC market.

Not quite, though that may be the future. For now, Microsoft requires secure-boot for all Windows8-certified hardware - however, for non-ARM hardware, they also require that the vendor provide a way to disable it.

So for now, at least, tablets and other ARM devices will be completely locked down (as they are for Apple now), but regular desktop/laptop hardware can be unlocked.